IMMUNOMODULATORY PROPERTIES OF CERTAIN AMINO-ACIDS INFLUENCE THE IMMUNOSTIMULATING PROPERTIES OF SPECIFIC PEPTIDES

Using the previously obtained data that amino acids could influence the thymus-dependent immune response, the significance of amino acids in the immunostimulating activity of peptides has been studied. The effect of seven synthetic fragments of murine Thy-1 antigen, non-sulfated cholecystokinin (CCK-8), the two tetrapeptides at the N- and C-terminal fragments of CCK-8, as well as neurotensin (NT) have been investigated. It has been found that both NT and those Thy-1 fragments which consisted of immunologically inert amino acids, did not influence the immune response in mice. CCK-8, its C-terminal fragment and those Thy-1-antigen peptides which contained immunoactive amino acids at C- or N-terminus or both, stimulated IgM-plaque forming cells (PFC) in animals. The N-terminal CCK-8 tetrapeptide showed negligible activity. The possibility of the existence of two amino acids based and the other dependent upon a sequence of amino acids in the peptide is being discussed.